Stable colloidal dispersions of molybdenum sulfide



United States Patent "ice 3,281,355 STABLE COLLOIDAL DISPERSIONS 0F MOLYBDENUM SULFIDE Elmer B. Cyphers, Cranford, and Max W. Hill, Westfield,

N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed Nov. 15, 1963, Ser. No. 323,887 14 Claims. (Cl. 252-18) The present application is a continuation-in-part of application Serial No. 99,688, filed March 31, 1961, and abandoned subsequent to the filing of the present application.

This invention relates to the preparation of compositions containing stably dispersed molybdenum sulfide of colloidal particle size and to the use of such compositions in lubricating oil formulations. Particularly, the inven tion relates to the formation of molybdenum sulfide in situ by the reaction of a molybdenum-containing compound with a sulfur-containing compound in the presence of a protective colloid or a dispersant-detergent.

Molybdenum sulfide has been recognized as an excellent lubricating material because of its outstanding reduction of wear and friction. This material has been widely used in the formulation of solid grease compositions. However, its insolubility in lubricating oil and its black color have militated against its use in liquid lubricant compositions such as crankcase oils for internal combustion engines. Many attempts to incorporate molybdenum sulfide into fluid oil have been made by grinding the molybdenum sulfide to an exceedingly fine particle size and then dispersing it in oil. Such dispersions still have a dark color and the solid particles tend to settle out of the oil during storage.

It has now been found that by preparing molybdenum sulfide in situ in the presence of certain protective colloidal materials it is possible to obtain stable dispersions which avoid the black color normally associated with molybdenum sulfide. While the molybdenum sulfide is preferably prepared by the reaction of a molybdenum salt and hydrogen sulfide, it is within the scope of the invention to employ other sources of the sulfide ion such as ammonium hydrosulfide, or ammonium polysulfide, or the corresponding alkali metal derivatives, e.g. sodium or potassium hydrosulfide or polysulfide. The protective colloidal materials are those materials which are known in the lubricating art as detergent additives. Since such detergent additives are normally added to automotive crankcase oils they can now be made to serve the additional function of stably suspending the molybdenum sulfide. The resulting compositions containing molybdenum sulfide show a marked tendency in reducing wear and friction as will be later demonstrated.

Stated more explicitly the process of this invention is conducted by reacting a water-soluble or a lower-alcoholsoluble salt of a compound of molybdenum in which compound the valence of molybdenum is at least four, with a reagent effective to furnish sulfide ions and thereby form molybdenum sulfide, the reaction being conducted in the presence of a lubricating oil detergent additive that is capable of stably suspending molybdenum sulfide in the lubricating oil.

Particularly useful molybdenum salts for forming the sulfide are those of the formula: X M0O wherein X represents a metal or an ammonium radical, and n is either 1 or 2, depending upon the valence of X. Specific examples of such molybdates include ammonium molybdate and alkali metal molybdates such as those of sodium or potassium.

Other molybdenum salts that may be used in aqueous solution include MoCl MoBr MoO Cl MoOCl 3,281,355 Patented Oct. 25, 1966 MOOzBI'g, MO2O3CI6, MO203C15, MOOF4. It is also POS- sible to employ aqueous sulfuric acid solutions of M00 or H MoO or molybdenum blue. Other suitable starting materials include solutions of molybdenum naphthenates or sulfonates in one or more of the lower alcohols. By lower alcohol is meant a C to C aliphatic alcohol, i.e., methanol, ethanol, isopropyl alcohol or butyl alcohol.

The formation of the molybdenum sulfide can be carried out in the presence of the detergent additive per se. It is usually more convenient, however, to carry out the formation in an oil concentrate of the detergent additive. These concentrates usually contain about 10 to Wt. percent of the detergent additive, with the remainder being lubricating oil.

The lubricating oil may be either a mineral oil or a synthetic oil. Examples of synthetic oils include synthetic hydrocarbon oils, polysilicones, polyglycols, dibasic acid esters such as di-2-ethyl hexyl sebacate, carbonate esters, glycol esters such as C oxo acid diesters of tetraethylene glycol, and complex esters, as for example the complex ester formed by the reaction of 1 mole of sebacic acid with 2 moles of tetraethylene glycol and 2 moles of 2-ethyl hexanoic acid. The mineral lubricating oils may be of any suitable type including those derived from the ordinary paraffinic, naphthenic, asphaltic or mixed base mineral crude oils by suitable refining methods.

The detergent additives which are operable as dispersants for the present invention include the petroleum sulfonates, synthetic alkyl aryl sulfonates, various alkyl phenates, alkyl phenate sulfides, phosphosulfurized olefin polymers, and various combinations of these additives. Following are specific descriptions of several of the above types of detergent additives.

Petroleum sulfonates generally used as lubricating oil detergents are the oil-soluble alkaline earth metal salts of high molecular weight sulfonic acids. These sulfonic acids are produced by the treatment of petroleum oils of the lubricating oil range with fuming sulfuric acid and generally have molecular weights of about 300 to 700. Petroleum sulfonates are well known in the art and have been described in numerous patents, e.g., US 2,467,176.

Detergent sulfonates can also be derived synthetically from relatively pure alkyl aryl sulfonic acids having from about 10 to 33 carbon atoms per molecule. For example, sulfonated products of alkylated aromatics such as benzene, toluene, xylene, and naphthalene, alkylated with olefins or olefin polymers of the type of polypropylene, polyisobutylene, etc., can be used.

Specific examples of the above two types of sulfonates include calcium petroleum sulfonate of about 880 molecular weight, barium petroleum sulfonate of about 980 molecular weight, calcium C alkyl benzene sulfonate, barium C alkyl benzene sulfonate and calcium C alkyl benzene sulfonate; wherein said C alkyl group is derived from diisobutylene; said C alkyl group is obtained from tripropylene and said C 5 alkyl group is obtained from tetraisobutylene.

The above sulfonates may be either neutral sulfonates, i.e. where the sulfonic acid is neutralized with an equal mole equivalent amount of metal base, or the sulfonates may be of the so-called high alkalinity type. In the latter case, additional metal base, in excess of that required for simple neutralization, is reacted with the sulfonic acid to form an alkaline product which can then be blown with carbon dioxide to reduce its alkalinity and form a substantially neutral final product. The term sulfonate as used herein and in the appended claims includes both neutral sulfonates and so-called high alkalinity (-or high metal content) sulfonates.

Metal salts of alkyl phenols and of alkyl phenol sulfides are also well known in the art. Metal salts of alkyl phenols having straight chain or branched chain alkylv groups of from 5 to 20 carbon atoms are usually preferred, and the metal used to form the phenate is preferably an alkaline earth metal, e.g., calcium, barium, strontium, or magnesium, although other salts such as those of aluminum, sodium, cobalt, lead, chromium or tin are sometimes used. A specific example is the barium salt of the alkylation product of phenol with tripropylene. Metal salts of the corresponding alkyl phenol sulfides may also be used. The latter are the thioethers and polysulfides of alkyl phenols, i.e. compounds in which the alkyl groups are joined by one or more divalent sulfur atoms. The alkyl phenols can be converted to phenol sulfides by reaction with sulfur dichloride. If sulfur monochloride is used, the resulting products are primarily alkyl phenol disulfides. Specific examples of the phenate sulfides include barium tertiary octyl phenol sulfide, calcium tertiary octyl phenol sulfide, barium-calcium nonyl phenol sulfide, barium tertiary amyl phenol sulfide, calcium dodecyl phenol sulfide, and barium nonyl phenol sulfide. High alkalinity (i.e. high metal content) phenates and phenate sulfides are also included in the above description. These materials are prepared by reacting the phenol sulfide with an excess of metal base and then neutralizing the basic product, generally by C blowing.

The phosphosulfurized olefin materials are also well known in the art. These materials are prepared by reacting an olefin or an olefin polymer with a sulfide of phosphorus, preferably P 8 The olefin polymers have Staudinger molecular weights in the range of from about 500 to about 200,000 and contain from 2 to 6 carbon atoms per olefin monomer. Polymers of ethylene, propylene or butylene may be used, for example. In general, the phosphosulfurized polyolefin is prepared by reacting the polyolefin with from 5 to 30 weight percent of a sulfide of phosphorus, and preferably with 10 to 20 weight percent of phosphorus pentasulfide. The phosphosulfurization reaction is conducted under anhydrous conditions at temperatures in the range of 150 to about 600 F. for from about k to hours. It is advisable to treat or blow the phosphosulfurized product with an inert gas such as nitrogen for a period of from 10 minutes to 2 hours to aid in reducing hydrogen sulfide evolution and its corresponding odor. The preparation of phosphosulfurized hydrocarbons and the use of catalysts in the phosphosulfurization reaction are more fully described in US. Patent 2,875,188.

Other detergent additives useful in this invention include the reaction products of phosphosulfurized hydrocarbons with alkaline earth metal oxides or hydroxides which can be prepared by first treating a hydrocarbon with the phosphorus sulfide and then reacting the product with an alkaline earth hydroxide or oxide, for example, barium hydroxide, preferably in the presence of carbon dioxide.

The dispersants of this invention may also include high molecular weight polymeric dispersants made with one or more polar monomers, such as vinyl acetate, vinyl pyrrolidone, methacrylates, fumarates and maleates. These dispersants have molecular weights in the range of about 500 to 50,000. One example is a copolymer of 65 to 85 weight percent of mixed C C fumarates, 10 to weight percent of vinyl acetate, and 5 to 15 weight percent of N-vinyl pyrrolidone. Another example is the copolymer derived by reaction of mixed tallow fumarates and C oxo fumarates, averaging about 420 molecular weight, with vinyl acetate in a 3 to l acet-ate-fumarate ratio, and 3 weight percent of maleic anhydride, followed by subsequent removal of excess vinyl acetate. By tallow fumarates is meant the esters of fumaric acid and the alcohols derived by hydrogenation of tallow. The latter are principally C and C alcohols with minor amounts of C C and C alcohols. C oxo alcohols are prepared by reaction of carbon monoxide and hydrogen on mixed C -C olefins followed by hydrogenation of the resulting aldehydes.

The molybdenum-sulfide-containing compositions of the invention are prepared by any number of methods, several of which follow:

A molybdenum salt such as ammonium molybdate is dissolved in water and the resulting solution is slowly added to heated detergent while bubbling hydrogen sulfide through the detergent. The temperature of the detergent during this addition is maintained in the range of about 250 to 600 F., preferably 275 to 425 F. Alternatively, all the aqueous solution of molybdenum salt is first added to the hot detergent, and then hydrogen sulfide is bubbled through the mixture. In either case, molybdenum sulfide is formed in situ and sufiicient heat is applied to boil off the water and to help promote the reaction between the hydrogen sulfide and the salt. For purposes of economy, it is preferred that the water solution of the molybdenum salt be saturated so as to minimize the amount of water to be later evaporated. Such a saturated solution will usually contain about 15 wt. percent of the salt in the use of ammonium molybdate. It is more preferred to add a small amount of a volatile acid such as hydrochloric acid or acetic acid, or ammonium hydroxide in order to increase the solubility of the molybdenum salt in water. In this way, saturated solutions containing as much as about 20% of the molybdenum salt can be obtained. As another alternate procedure, the aqueous solution of molybdenum salt can be added to the detergent at room temperature and hydrogen sulfide bubbled through the mixture.

Since many lubricating oil detergent additives are also emulsifiers, an emulsion may be formed between the aqueous solution and the detergent or the oil concentrate containing the detergent. This emulsion results in intimate contacting of the molybdenum sulfide particles with a protective coating of detergent additive as soon as the molybdenum sulfide particles are formed. When the reaction is completed and agitation discontinued, then various emulsion breakers such as C to C alcohol or sodium chloride can be added to the reaction mixture. When the emulsion breaks, the water layer can then be decanted and the remainder of the material can be heated to dryness. Or the use of emulsion breakers can be dispensed with and all of the water can be evaporated by simply heating the reaction product until a dry product is obtained.

In any case, it will be generally preferred to filter the final material to remove any molybdenum sulfide which may have precipitated. Thus, in practice, it has been found difiicult to disperse more than about 2.0 Wt. percent based on the total final reaction product, of molybdenum sulfide. Amounts of molybdenum sulfide in excess of this will generally precipitate from solution, but are easily removed by simple filtration.

In an alternative procedure, an organic molybdenum salt such as molybdenum naphthenate is dissolved in alcohol and added slowly to the detergent at room temperature while stirring and bubbling hydrogen sulfide through the mixture, followed by heating to remove the alcohol while continuing the addition of hydrogen sulfide. After all the alcohol is removed, the mixture is filtered.

In still another embodiment of this invention, separate aqueous solutions of ammonium molybdate and ammonium polysulfide are simultaneously added dropwise to the detergent while stirring vigorously at room temperature. The aqueous layer is then separated by adding sufficient alcohol and heptane to produce two discrete layers, separating the layers, discarding the aqueous layer, and evaporating the solvent from the detergent mixture, which is finally filtered.

While the above procedures represent preferred methods of forming the molybdenum sulfide, actually it is only essential that the molybdenum sulfide be formed in the presnce of the detergent additive and this may be accomplished in any manner.

The final oil compositions of the invention will comprise a major proportion of lubricating oil and about 4 hours.

0.001 to 1.5 weight percent of finely dispersed molybdenum sulfide and about 0.1 to 20 weight percent of a lubricating oil detergent additive. Preferred proportions are 0.005 to 0.5 wt. percent of molybdenum sulfide and 2 to wt. percent detergent.

Various conventional lubricating oil additives may also be incorporated in the composition of the invention to form finished motor oil lubricants or other oil compositions such as turbine oils, hydraulic fluids, transmission fluids, industrial oils, or the like. For example, additives in the amounts of 0.1 to 10 weight percent may be added, such as pour point depressants, e.g. Waxalkylated naphthalene or copolymers of vinyl acetate and alkyl fumarates, V.I. improvers such as polymethacrylates or polyisobutylene, anti-oxidants such as 2,6 ditertiary butyl para cresol, phenyl-alpha-naphthylamine, hydroquinone monoalkyl ether, or bisphenols, dyes, etc.

The invention will be further understood by the following examples:

EXAMPLE 1 Part A.Detergent Concentrate A, used in this example consisted of about 70 wt. percent of a detergent additive and about 30 wt. percent mineral lubricating oil. The detergent additive itself was prepared by heating a mixture consisting of about 40 wt. percent of a phosphosulfurized polyisobutylene, 30 wt. percent of an oil concentrate of a high barium content tertiary octyl phenol sulfide and about 30 wt. percent of an oil solution containing 60 wt. percent of a high barium content synthetic sulfonate.

The phosphosulfurized polyisobutylene was prepared by reacting polyisobutylene of about 1100 molecular weight with 'wt. percent based on the weight of polyisobutylene, of P 8 at about 425 F. for about 8 hours under a nitrogen atmosphere. The oil concentrate of the barium tertiary octyl phenol sulfide consisted of about 43 wt. percent of the said sulfide and about 57 wt. percent of a mineral lubricating oil. The barium tertiary octyl phenol sulfide was of the high alkalinity type having an alkaline neutralization number of about 90 and contained about 12 wt. percent barium.

The high barium sulfonate had a barium content of about 14 wt. percent based on the weight of the sulfonate. The sulfonic acid portion of the sulfonate was prepared by alkylating benzene with polypropylene, said sulfonic acid portion having an average molecular weight of about 440 of which 75 wt. percent of the sulfonic acid radicals had a molecular weight greater than 400. This sulfonate was prepared by reacting neutral barium sulfonate with additional barium hydroxide followed by neutralizing by bubbling carbon dioxide through the sulfonate.

The mixture of phosphosulfurized polyisobutylene, barium tertiary octyl phenol sulfide, and barium sulfonate was heated at 350 F. for about 12 hours and filtered to produce the Detergent Concentrate A.

Part B.-A dispersion of molybdenum sulfide and detergent additive was prepared as follows: A substantially saturated solution was prepared by dissolving 160 grams of ammonium molybdate having the formula: (NI-I Mo O -4H O in 500 grams of water and 90 grams of concentrated ammonium hydroxide. Into an open stainless steel pot was placed 3200 grams of Detergent Concentrate A. Detrgent Concentrate A was stirred and heated under a hood to a temperature of about 325 F. The aforementioned aqueous solution of the ammonium molybdate was slowly added to the hot detergent concentrate over a period of about 160 minutes. The mixture was further heated at 325 F., after the water had evaporated, and then hydrogen sulfide was added, while stirring the mixture over a period of about Excess hydrogen sulfide was thus utilized in order to insure complete reaction of all molybdate. The reaction mass was then filtered hot through diatomaceous earth in a Buchner funnel to remove any precipitated particles of molybdenum sulfide.

The filtered product was a clear, brown liquid which remained clear and stable indefinitely at room temperature and analyzed about 1.1 wt. percent molybdenum metal. A 5% blend of the filtered product in white oil showed a nephelometer reading of 18, which was the same as the original unreacted Detergent Concentrate A, and was perfectly clear to the naked eye.

EXAMPLE 2 A base stock blend was prepared from:

Parts Low cold test coastal distillate of 76 SUS/ 100 F.

and 63 V1. 46.9 Mid-Continent neutral-150 SUS/ 100 F. and

100 V.I. 46.9 Additive B 5.0 Acryloid 710 1.0 Additive C 0.2

The inspections on this base stock blend are:

Gravity API 30.8 SUS.VIS/100 F. 181.3 SUS.VIS/210 F. 48.6

Pour, F. 35 Cloud, F. 6 Flash COC, F. 360 Fire COC, F. 385

Additive B was a 33 wt. percent solution of polyisobutylene of about 10,000 molecular weight in 67 wt. percent of a solvent neutral mineral oil of 150 SUS. viscosity at 100 F. The Acryloid 710 was a polymethacrylate viscosity index improver.

Additive C consisted of 37 /2 volume percent of a copolymer of Lorol B fumarate and vinyl acetate, 12.5 volume percent of the condensation product of chlorinated wax and naphthalene and 50 volume percent of a neutral mineral oil of 45 SUS. at 100 F. The copolymer is primarily a viscosity index improver while the condensation product is a pour depressant.

5.0 wt. percent of the filtered molybdenum sulfide product of Example 1 was added by simply mixing to 95.0 wt. percent of the above described base stock blend. The resulting final product represents a fully formulated crankcase motor oil. This final product containing the molybdenum sulfide, and also the base stock per se, i.e. without the molybdenum sulfide, were tested in a Kinematic Oiliness Test Machine (KOTM). This machine and test are completely described in US. Patent No. 2,909,056. The KOTM machine comprises 3 steel friction buttons contacting by an annular track, with means for applying weights to the friction buttons. Both the track and buttons are immersed in a bath of the lubricant to be tested. As the track rotates, it exerts a drag upon the friction buttons, which drag can be measured. The results of this KOTM test, as well as of other well-known conventional load-carrying tests are summarized in Table I.

TABLE I Base 5.0% BIOS-,1 Laboratory Tests Units Stock Sol in Base Stock KOTM (Steel Buttons and Poor Very Good Track). 4 Ball Wear Test mm 0. 49 0. 25 4 Ball E. P. Test:

Seizure Load Kg 71 Weld Load Kg 112 200 SAikE tMachine, 14.6/1 Slip Scale 1105.. 20 55 a lo. Almen Test, Gradual Loading 2 lb. wts 11 Timken OK Timd Lbs. 5 Falex Machine Lbs. 1, 250

7 EXAMPLE 3 'A lubricating oil composition was prepared by mixing -4.5 wt. percent of the filtered molybdenum sulfide product of Example 1 with 95.5 wt. percent of a base stock containing mineral lubricating oil, a polymeric viscosity index improver, a pour point depressant and a small amount of a zinc dialkyl dithiophosphate as antioxidant. The resulting composition was tested in the L-l Caterpillar Test. For comparison purposes, 4.5 wt. percent of Detergent Concentrate A (previously described) was added to 95.5 wt. percent of the same base stock, and the resulting comparison composition was also tested in the well-known L-l Caterpillar Test. The results obtained are summarized in Table II.

TABLE II With Without L-l Caterpillar Test Molybdenum Molybdenum Sulfi e Sulfide 120 Hours:

Ring Zone, Demerit 0.09 0.16 Lower Ring Zone Area, Demerit 0.01 0.01 Top Groove Fill, Percent 1.0 1. 240 Hours:

Ring Zone, Demerit 0.28 0.56 Lower Ring Zone Area, Demerit 0.01 0.02 Top Groove Fill, Percent 8 16 As seen by the table, the molybdenum sulfide con taining composition was superior in cleanliness as measured by ring zone, lower ring zone area and top groove fill demerits, when compared to the exact same composition, but containing no molybdenum sulfide.

EXAMPLE 4 A molybdenum sulfide sol was prepared in a similar manner to that described in Example 1, but instead of using Detergent Concentrate A, an additive concentrate was used which consisted of about 40 wt. percent of high alkalinity barium-calcium nonyl phenol sulfide in 60 wt. percent mineral oil. The resulting product, after being filtered, analyzed 0.68% molybdenum.

EXAMPLE 5 A molybdenum sulfide sol was prepared in a manner similar to that described in Example 1, except that in place of Detergent Concentrate A, the detergent concentrate consisted of about 40 wt. percent of an overbased barium salt of an alkyl phenol sulfide in about 60 wt. percent mineral lubricating oil. The resulting product, after being filtered, analyzed about 0.31 wt. percent molybdenum.

EXAMPLE 6 be utilized in forming the molybdenum sulfide protective sol. For example, Example 1 can be repeated but using a P S -treated polyisobutylene of the type previously described as the suspending detergent in place of Detergent Concentrate A.

EXAMPLE 7 As still another example of the invention, Example 1 is exactly repeated but in place of the 3200 grams of Detergent Concentrate A, 3200 grams of a concentrate is used consisting of 40 weight percent of the neutral will stably suspend the molybdenum sulfide in oil can be used.

EXAMPLE 8 A solution of 12.5 grams of 85% molybdic oxide in 300 grams of water was prepared by adding NH OH to clear the solution. The solution was then acidified with H and 9 grams excess of H 80 added. Then, 500 grams of phosphosulfurized polyisobutylene diluted with 200 grams of heptane to reduce its viscosity was stirred in a 2-liter beaker at room temperature and treated with H 8 by bubbling the gas through it continuously while, at the same time, adding the above molybdic acid solution slowlyover a' period of 2 hours with vigorous stirring. The H 8 treatment was continued one hour after all the solution had been added.

The mixture was transferred to a 4-liter separatory funnel and enough heptane and isopropyl alcohol added to produce two separate layers. The aqueous layer, containing alcohol and some precipitated molybdenum sulfide was discarded. The upper layer was filtered and the heptane stripped off by nitrogen blowing on a steam bath. The product was clear and stable and showed 0.53% M0 by analysis. The phosphosulfurized polyisobutylene employed in this example was prepared as described in Us. Patent 2,969,324, column 10, lines 12-26 (Intermediate 3).

EXAMPLE 9 Part APreparati0n 0 molybdenum blue After 50 grams of molybdic oxide was stirred into 500 grams of water, 50 grams of conceneration NH OH solution was added to produce a clear aqueous solution. To this was added 150 grams of concentration H 80 slowly with stirring. After cooling to about '100" F., 3 grams of aluminum foil was added and stirring continued overnight. A light blue color developed. The following morning the solution was heated to 130 F. and maintained between and F. for about 4 hours. A deep blue color developed, indicating the formation of molybdenum blue, a colloidal aqueous dispersion reported in the literature to have the composi tion MoO XH O. Stirring was continued for 40 hours and the solution which contained some blue precipitate, was then filtered.

The filtrate was a clear deep blue solution (692 gms.), The filter cake, which was also deep blue, was extracted with additional water resulting in substantially complete recovery of the blue cake in the form of a deep blue aqueous solution (154 grams).

Part BPreparati0n of molybdenum sulfide sol 400 grams of Detergent A was placed into a 2,000 ml. beaker and stirred continuously at room temperature. H 8 gas was bubbled through the mixture while the larger portion of the molybdenum blue solution from 'part A was added slowly over a period of 70 minutes. The H S gas addition was continued for one hour longer. Then the smaller portion of the molybdenum blue solution was added slowly over a period of 35 minutes and H S flow was again continued for one more hour.

'After standing about 40 hours there was no separation of water and detergent. The mixture was therefore transferred to a 6-liter separatory funnel and heptane, isopropyl alcohol, and water were added until two distinct layers formed.

This method of emulsion breaking is well known to those skilled in the art. The amount of each ingredient to be added is guided by the appearance of the emulsion. For example, if the emulsion is white, alcohol is added until it becomes relatively clear. Then heptane and water are added alternately to increase the difference in density of the layers. If whiteness again develops, more alcohol is added and the steps are repeated. While no exact record of individual additions was kept, it is estimated that the final mixture contained in the range of 1015% of detergent, 2535% of heptane, 10-20% of isopropyl alcohol, and 35-50% of water.

After the two distinct layers had formed, the aqueous layer containing most of the alcohol and some precipitated molybdenum sulfide was discarded. The heptane solution, containing the detergent with colloidally dispersed molybdenum sulfide, was filtered and the heptane stripped off by blowing with nitrogen on a steam bath, followed by heating in a vacuum oven. The product was clear and stable and showed 0.85% M by analysis.

EXAMPLE "10 A sol of molybdenum sulfide in detergent additive is prepared as follows:

A solution of 200 grams of molybdenum tetrabromide, MoBr in 1000 grams of water is slowly added to 3200 grams of Detergent Concentrate A with constant stirring at a temperature of 325 F. as in Example 1. The resulting product is then treated with an excess of hydrogen sulfide and filtered to produce a clear, stable sol of molybdenum sulfide.

EXAMPLE 11 After 3,200 grams of Detergent Concentrate A has been stirred and heated to 350 F. and saturated with H S gas, an aqueous solution made by dissolving 100 grams of molybdenum dioxydichloride in 1,000 grams of water is added slowly, while simultaneously adding H 8 to maintain an excess of H 8. The resulting product is filtered to produce a clear, stable sol of molybdenum sulfide.

EXAMPLE 12 Two mols of ammonium hydrosulfide are dissolved in sufficient water to make 250 ml. of solution and placed in a graduated dropping funnel A. Then, 0.4 mol of ammonium molybdate and 20 ml. of concentrated ammonium hydroxide are dissolved in sufficient water to make 250 ml. of solution and placed in a graduated dropping funnel B. Then 500 grams of Detergent Concentrate A are placed in a 3-liter beaker equipped with an efiicient stirrer.

While stirring Detergent Concentrate A, the contents of dropping funnels A and B are added dropwise over a period of 2 to 3 hours, taking care that approximately equal amounts of each solution are added in any given time interval. After .all of the aqueous solutions are added, stirring is continued for one hour.

The mixture is then transferred to a 6-liter separatory funnel and treated as in Example 9 to break the emulsion, separate the water, evaporate the solvent and remove any precipitate by filtration.

As demonstrated above, concentrates containing 0.1 to as much as about 2.0 wt. percent of molybdenum sulfide with about to 80 wt. percent detergent additive (active ingredient basis) in oil are readily prepared by the techniques of this invention. These concentrates can then be added to lubricating oil compositions to give finished lubricants containing 0.001 to 1.5, preferably 0.005 to 0.5 wt. percent of the molybdenum sulfide.

It is to be understood that the examples presented herein are intended to be merely illustrative of the invention and not as limiting it in any manner; nor is the invention to be limited by any theory regarding its opera-bility. The scope of the invention is to be determined by the appended claims.

What is claimed is: q q

1. A method for preparing a stable dispersion of molybdenum sulfide which comprises the steps of: preparing a mixture of a lubricating oil detergent additive, capable of stably suspending molybdenum sulfide in lubricating oil, and a solution of a molybdenum compound dissolved in a solvent selected from the group consisting of water and C to C aliphatic alcohols, said molybdenum compound being characterized by having a molybdenum atom with a valence of at least four and by being soluble in a solvent selected from the group consisting of water and C to C aliphatic alcohols; contacting said mixture with a reagent effective to furnish sulfide ions, whereby finely dispersed molybdenum sulfide is formed; and removing said solvent fr-om the reaction mixture.

2. A method according to claim 1 wherein said reaction mixture is heated to facilitate solvent removal and to promote the formation of molybdenum sulfide.

3. A method according to claim 1 wherein said molybdenum compound is a molybdate having the general formula:

wherein X is a member selected from the group consisting of ammonium radicals and metal, and wherein n is a number from 1 to 2.

4. A method according to claim 1 wherein said reagent comprises hydrogen sulfide.

5. A method according to claim 1 wherein said reagent comprises a sulfide from the class consisting of alkali metal hydrosulfides, alkali metal polysul-fides, ammonium hydrosulfide and ammonium polysulfide.

6. A method as defined by claim 1 wherein said lubricating oil detergent additive is an alkaline earth metal sulfonate.

7. A method as defined by claim 1 wherein said lubricating oil detergent additive is a metal salt of an alkyl phenol sulfide.

8. A method as defined by claim 1 wherein said lubricating oil detergent additive is a phosphosulfurized polyisobutylene.

9. A method of preparing a stable dispersion of molybdenum sulfide in a lubricating oil which comprises mixing an aqueous solution of water-soluble molybate with a lubricating oil containing a lubricating oil detergent additive capable of stably dispersing molybdenum sulfide in said lubricating oil, passing hydrogen sulfide through the resulting mixture to form molybdenum sulfide, and removing water to form a dry product.

10. A stable lubricating oil composition comprising a major amount of a mineral lubricating oil, about 0.005 to 0.5 wt. percent of molybdenum sulfide in the form of a stable dispersion and about 2 to 10 wt. percent of a lubricating detergent additive capable of stably suspending molybdenum sulfide in said lubricating oil, said molybdenum sulfide dispersion having been prepared by converting a soluble molybdenum compound to molybdenum sulfide in the presence of said detergent additive, said soluble molybdenum compound being selected from the group consisting of Water-soluble and lower-alcohol-soluble molybdenum compounds in which molybdenum has a valence of at least four.

11. A stable lubricating oil composition comprising from about 0.1 to wt. percent of a lubricating oil detergent additive capable of stably suspending molybdenum sulfide in a lubricating oil, from about 0.001 to 1.5 wt. percent of molybdenum sulfide in the form of a stable dispersion, and the remainder a lubricating oil, said molybdenum sulfide dispersion having been prepared by converting a soluble molybdenum compound to molybdenum sulfide in the presence of said detergent additive, said soluble molybdenum compound being selected from the group consisting of water-soluble and lower-alcoholsoluble molybdenum compounds in which molybdenum has a valence of at least four.

12.. A stable lubricating oil additive concentrate comprising from about 10 to 80 Wt. percent of a lubricating oil detergent additive capable of stably suspending molybdenum sulfide in a lubricating oil, from about 01 to 2.0 Wt. percent of molybdenum sulfide in the form of a stable dispersion, and the remainder a lubricating oil, said molybdenum sulfide dispersion having been prepared by converting a soluble molybdenum compound to molybdenum sulfide in the presence of said detergent additive, said soluble molybdenum compound being selected from the group consisting of water-soluble and lower-alcoholsoluble molybdenum compounds in which molybdenum has a valence of at least four.

13. A stable lubricating oil composition comprising from about 0.1 to 80 wt. percent of a lubricating oil detergent additive capable of stably suspending molybdenum sulfide in a lubricating oil, from about 0.001 to 1.5 Wt. percent of molybdenum sulfide in the form of a stable dispersion, and the remainder a lubricating oil, said molybdenum sulfide dispersion having been prepared by converting a water-soluble molybdate salt to molybdenum sulfide in the presence of said detergent additive.

14. A stable dispersion of molybdenum sulfide comprising a major proportion of a lubricating oil detergent additive capable of stably suspending molybdenum sulfide References Cited by the Examiner UNITED STATES PATENTS 2,609,342 9/1952 White et al. 25225 2,619,458 11/1952 McBride 252-25 2,781,314 2/1957 Wasson 252-25 2,956,018 10/1960 Carlyle et :al. 25218 3,057,896 10/1962 Schlicht et al. 252-18 FOREIGN PATENTS 570,814 2/1959 Canada. 574,161 4/1959 Canada.

DANIEL E. WYMAN, Primary Examiner.

L. G. XIARHOS, Assistant Examiner. 

1. A METHOD FOR PREPARING A STABLE DISPERSION OF MOLYBDENUM SULFIDE WHICH COMPRISES THE STEPS OF: PREPARING A MIXTURE OF A LUBRICATING OIL DETETGENT ADDITIVE, CAPABLE OF STABLE SUSPENDING MOLYBDENUM SULFIDE IN LUBRICATING OIL, AND A SOLUTION OF A MOLYBDENUM COMPOUND DISSOLVED IN A SOLVENT SELECTED FROM THE GROUP CONSISTING OF WATER AND C1 TO C4 ALIPHATIC ALCOHOLS, SAID MOLYBDENUM COMPOUND BEING CHARACTERIZED BY HAVING A MOLYBDENUM ATOMS WITH A VALENCE OF AT LEAST FOUR AND BY BEING SOLUBLE IN A SOLVENT SELECTED FROM THE GROUP CONSISTING OF WATER AND C1 TO C4 ALIPHATIC ALCOHOLS; CONTACTING SAID MIXTURE WITH A REAGENT EFFECTIVE TO FURNISH SULFIDE IONS, WHEREBY FINELY DISPERSED MOLYBDENUM SULFIDE IS FORMED; AND REMOVING SAID SOLVENT FROM THE REACTION MIXTURE.
 6. A METHOD AS DEFINED BY CLAIM 1 WHEREIN SAID LUBRICATING OIL DETERGENT ADDITIVE IS ALKALINE EARTH METAL SULFONATE. 